Functions
2.18 Reverse-Power Protection Application with Flexible Protection Function
SIPROTEC, 7SJ62/64, Manual
C53000-G1140-C207-2, Release date 01.2008
300
2.18.2 Implementation of the Reverse Power Protection
General
The names of messages can be edited in DIGSI and adjusted accordingly for this example. The names of the
parameters are fixed.
Determination of the Reverse Power
The reverse power protection evaluates the active power from the symmetrical components of the fundamental
harmonics of the voltages and currents. The evaluation of the positive sequence systems causes reverse
power determination to be independent of the asymmetries in currents and voltages and reflects the real load
of the driving end. The calculated active power value corresponds to the total active power. The connection in
the example illustrates positive measurement of power in the direction extending from the busbar to the trans-
former of the device.
Functional Logic
The following logic diagram depicts the functional logic of the reverse power protection.
Figure 2-109 Logic diagram of the reverse power determination with flexible protection function
The reverse power protection picks up once the configured pickup threshold has been exceeded. If the pickup
condition persists during the equally settable pickup delay, the pickup message P. rev. P U is generated and
starts the trip delay time. If the pickup condition does not drop out while the trip delay time is counting down,
the trip indication P. rev. TRIP and the timeout indication P. rev. timeout are generated. The picked up element
drops out when the value falls below the dropout threshold. The blocking input >P rev. block blocks the entire
function, i.e. pickup, trip and running times are reset. After the blocking has been released, the reverse power
must exceed the pickup threshold and both times must run out before the protection function trips.
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